As the demand for enjoying movies using high-quality images and sounds increases, the importance of more dynamic and realistic sounds continues to increase. Accordingly, the number of consumers who spare no expense to purchase not only video apparatuses, such as projectors or large-sized displays, but also high-multichannel speaker systems is gradually increasing.
Representative digital audio formats include a format for 5.1 channel audio and a format for 7.1 channel sound.
5.1 channel sound is a method in which 5 speakers are disposed on left, center and right sides in front of a listener and on left and right sides behind the listener and a (0.1 channel) subwoofer adapted to augment low-pitched sound is separately configured. The front left and right and rear left and right speakers function to provide a three-dimensional (3D) sound effect for a fixed listener, and the front center speaker functions to fix the conversation of a performer on a screen on the front screen for the sake of a moving listener. Representative 5.1 channel sound methods include Dolby digital 5.1, known as AC-3 format, and DTS (Digital Theater Systems).
7.1 channel sound is a surround sound listening method composed of 7 directional speakers and a single subwoofer. 7.1 channel sound is a method that improves a 3D effect by adding 2 speakers on either side of conventional 5.1 channels composed of 5 directional speakers and a single subwoofer.
FIG. 1 shows diagrams showing the sound fields of representative 5.1 channel sound and representative 7.1 channel sound.
Referring to FIG. 1, in the case of general 5.1 channel sound 110, 3 channels L, C and R, two surround channels Ls and Rs and a subwoofer LFE are provided on the front side thereof. In the case of 5.1 channel-EX sound 120, a center surround channel Cs is added to the general 5.1 channel sound 110. In 7.1 channel-DS sound 130, the center surround channel is divided into two channels Lrs and Rrs in the 5.1 channel-EX sound 120. In 7.1 channel-SDDS sound 140, two channels Lc and Rc are added among three front channels in the general 5.1 channel sound 110.
Apart from the 5.1 channel sound and the 7.1 channel sound shown in FIG. 1, Korean Patent Application Publication No. 10-2009-0100566 discloses a high-multichannel speaker system in which a plurality of small-sized speakers is arranged behind a display monitor in order to provide more realistic high-quality 3D sound.
FIG. 2 is a diagram showing a display screen disclosed in Korean Patent Application Publication No. 10-2009-0100566 and a high-multichannel array speaker system arranged behind the display screen.
Referring to FIG. 2, it can be seen that 2D-array speakers are arranged behind a display screen and sounds are output in association with the objects of a displayed screen.
In order to output sounds in association with objects via the array speakers behind the screen, conventional 5.1 channel sound and 7.1 channel sound are insufficient, and more audio channels must be assigned.
For example, if the number of speakers arranged behind the screen is 15, 12 additional audio channels are required compared to conventional 5.1 channels in which 3 speakers are arranged behind a screen.
Furthermore, one of the important issues of high-multichannel audio systems is compatibility with a conventional 5.1 channel sound system or 7.1 channel sound system. That is, even when the same digital audio packet is provided to a theater, sound must be able to be output via a larger number of channels, i.e., 5.1 channels, 7.1 channels or 16 or more channels in accordance with the sound system environment of the theater.
Accordingly, there is an urgent need for new encoding/decoding technology that can efficiently encode high-multichannel audio as well as conventional 5.1 channel audio and conventional 7.1 channel audio.